1. Field of the Invention
The present invention relates to a fuel supply apparatus supplying fuel to an internal combustion engine and a method for controlling the fuel supply apparatus.
2. Description of the Related Art
Japanese Unexamined Patent Publication No.07-091330 discloses a fuel vapor purge system which traps fuel vapor generated inside a fuel tank in a canister, and which purges the fuel vapor trapped in the canister, into an intake passage via a purge passage at which a purge control valve is provided.
Further, the above Publication discloses a method for diagnosing whether there is any leak at the above-described fuel vapor purge system.
In the leak diagnosis, a drain cut valve is provided at a fresh air intake of the canister, and a discharge opening of an air pump is connected along the purge passage at the downstream of the purge control valve.
Here, due to air being supplied to the purge passage by the air pump in a state in which the drain cut valve and the purge control valve are closed, a diagnostic zone including the purge passage, the canister, and the fuel tank is pressurized.
Then, it is diagnosed whether there is any leak on the basis of a change of pressure in the diagnostic zone accompanying the pressurization.
By the way, in addition to providing the fuel vapor purge system, when a drain cut valve, an air pump, a pressure sensor, or the like which are for a leak diagnosis are provided thereat, there has been the problem that a large number of controlled system parts and sensors in the fuel supply apparatus are used, and the wirings with a control unit are made longer and complicated.